Traditionally, outdoor lighting systems include a plurality of lamps connected to a transformer. There may be one or more “legs” or sets of wires coming out of the transformer, each connected to at least one light. A timer box connects to the transformer. The user programs the on/off times and all of the lights energize in unison, such that all lights connected to a particular transformer turn ON or OFF together regardless of which leg they are on.
Some manufacturers provide lighting systems with addressable lighting modules. The timer box of the traditional lighting system is replaced with a lighting controller that supplies the lighting modules with a separate power and data signal. Each lighting module has an address and is independently addressable by the lighting controller via the data signal. These networked lighting systems provide the lighting modules with two sets of wires instead of the one or more legs. One set provides a power signal to illuminate the lamps or LEDs and a second set provides the lighting module with a data signal. The user programs the lighting controller to turn-on and turn-off lights at individual addresses such that a single light can turn-on or turn-off independently of the other lights in the network, when, for example, the data signal carries the address of a particular light.
In some instances, the power signal is the output of a low voltage power transformer which is connected directly to the lighting modules to power the lamps or LEDs. For example, a primary AC to 12 VAC transformer accepts 120 VAC and outputs 12 VAC, where the 12 VAC power signal electrically couples directly to the lighting modules and powers the lamps/LEDs.
In other instances, the power signal is the output of a DC switching power supply. For example, a DC switching power supply accepts 120 VAC and outputs 12 VDC, where the 12 VDC power signal electrically couples directly to the lighting modules and powers the lamps/LEDs.
Other manufacturers of addressable lighting systems send power and data to the lighting modules on the primary power wires. The user programs the lighting controller to turn-on and turn-off lights at individual addresses such that a single light can turn-on or turn-off independently of the other lights in the network. In some instances, these lighting systems use a high frequency carrier, such as 125 KHZ, and superimpose this signal on the power line. This approach requires fairly large inductors, or complex Digital Signal Processors (DSPs) to decode the data contained in the carrier. One such commercially available system is the X10 control system originally developed by Pico Electronics of Glenrothes, Scotland.
In other instances, these lighting systems amplify the data signal to the level that can be used to power the lighting modules. For example, a PWM stepper motor driver chip can amplify a 0 volt to 5 volt transistor-transistor logic (TTL) data signal to positive 24 volts to reflect a logical one and negative 24 volts to reflect a logical zero. The amplified data signal electrically couples to the lighting module, where the voltage is sufficient to supply power to the lamps/LEDs while maintaining the logical data values of the data stream.